Providing End-to-End Delay Guarantees for Multi-hop Wireless Sensor Networks over Unreliable Channels

Wireless sensor networks have been increasingly used for real-time surveillance over large areas. In such applications, it is important to support end-to-end delay constraints for packet deliveries even when the corresponding flows require multi-hop transmissions. In addition to delay constraints, each flow of real-time surveillance may require some guarantees on throughput of packets that meet the delay constraints. Further, as wireless sensor networks are usually deployed in challenging environments, it is important to specifically consider the effects of unreliable wireless transmissions. In this paper, we study the problem of providing end-to-end delay guarantees for multi-hop wireless networks. We propose a model that jointly considers the end-to-end delay constraints and throughput requirements of flows, the need for multi-hop transmissions, and the unreliable nature of wireless transmissions. We develop a framework for designing feasibility-optimal policies. We then demonstrate the utility of this framework by considering two types of systems: one where sensors are equipped with full-duplex radios, and the other where sensors are equipped with half-duplex radios. When sensors are equipped with full-duplex radios, we propose an online distributed scheduling policy and proves the policy is feasibility-optimal. We also provide a heuristic for systems where sensors are equipped with half-duplex radios. We show that this heuristic is still feasibility-optimal for some topologies

Development of the Integrated Model of the Automotive Product Quality Assessment

Issues on building an integrated model of the automotive product quality assessment are studied herein basing on widely applicable methods and models of the quality assessment. A conceptual model of the automotive product quality system meeting customer requirements has been developed. Typical characteristics of modern industrial production are an increase in the production dynamism that determines the product properties; a continuous increase in the volume of information required for decision-making, an increased role of knowledge and high technologies implementing absolutely new scientific and technical ideas. To solve the problem of increasing the automotive product quality, a conceptual structural and hierarchical model is offered to ensure its quality as a closed system with feedback between the regulatory, manufacturing, and information modules, responsible for formation of the product quality at all stages of its life cycle. The three module model of the system of the industrial product quality assurance is considered to be universal and to give the opportunity to explore processes of any complexity while solving theoretical and practical problems of the quality assessment and prediction for products for various purposes, including automotive

The intellectual capital - environmental practices, performance and their relationships in the Romanian banking sector

Purpose – This paper reviews the knowledge assets that can be capitalized for successful Green Supply Chain Management (GSCM) implementation in the Romanian banking industry. GSCM is defined as the company’s ability to understand and manage the environmental risks along the Supply Chain (SC) (Carter and Rogers,2008). Banks are very much members of the SCs (McKenzie and Wolfe, 2004), called to integrate the environmental management into both operational and core commercial activities and to manage the environmental risk in their supply chain (FORGE Group,2000; International Finance Corporation, 2006; UNEP Finance Initiative, 2009a). Intellectual capital, or the ‘stock’ of knowledge-based equity firms hold, is recognized as a key contributor to their competitiveness (Bontis et al., 1999), which may act as a driver of environmental pro-activeness (Bernauer et al., 2006; Wu et al., 2007), as well as an obstacle in the process to design and implement GSCM (Post and Altman, 1994; Baresel-Bofinger et al., 2007), while organizational learning is seen as the key component in overcoming the organizational obstacles to environmental changes (Post and Altman, 1992; Post and Altman, 1994; Anderson and Wolff, 1996). Design/methodology/approach – This research paper describes the empirical results of a cross-sectional design employed in a sample of 41 banks operating in Romania with the purpose a. to explore the stage of designing and implementing GSCM practices in the Romanian banking sector; b. to determine which GSCM practices tend to be followed the most, c. which are the bank managers’ perceived benefits from implementing GSCM practices, as well as perceived obstacles in GSCM implementation in the banking sector; and d. what is the relationship between the aforementioned variables. For these purposes several statistical analyses were used, including both descriptive and inferential statistics. Originality/value – This is the first study looking for GSCM issues in the Romanian banking industry. The results of this research provide insights into what extent knowledge assets could be capitalized for successful Green Supply Chain Management implementation in the Romanian banking industry. Furthermore, it is increasing the ecological awareness, the theoretical and managerial insights for an effective implementation of GSCM practices in the banking sector. The analysis reveals that GSCM practices (especially practices in the immaterial flow) are strongly and significantly correlated with perceived benefits and pressures. However,this should be addressed in future research because the present study offers only correlational data and cannot establish causation. The study also concludes that bank’s size and foreign/Romanian ownership do not influence at all the level of GSCM practices implementation and related perceptions (pressures, obstacles,benefits) in the Romanian banking sector. Practical implications – The findings of this paper point to the conclusion that the banking sector in Romania is at a somehow advanced stage of ecological adaptation in the physical flow and at an early stage in the immaterial and commercial flows. Based on the literature and study’s findings, regarding the role that the management of intellectual capital and knowledge flow plays, several recommendations are proposed for enhancing the implementation process of GSCM practices in the banking industry in Romania

Towards a versatile transport protocol

n the context of a reconfigurable transport protocol, this paper introduces two protocol instances based on the com- position and specialisation of the TFRC congestion control and Selective Acknowledgment mechanisms. The two result- ing transport architectures lead respectively to the QTP_AF protocol, specifically designed to operate over QoS-enabled networks and the QTP_light protocol, specifically designed for resource-limited end systems connected to powerful servers. QTP_AF combines QoS-aware TFRC congestion control with full reliability to provide a transport service similar to TCP but additionally taking into account network-level band-width reservations. QTP_light proposes a modification of TFRC that shifts from the receiver to the sender the complexity of the loss rate estimation mechanism. This modification allows to alleviate the processing and communication load of "light" resource limited mobile receivers. We present the concept of these protocols and their adaptation in the EuQoS European project framework

Optimization of Free Space Optical Wireless Network for Cellular Backhauling

With densification of nodes in cellular networks, free space optic (FSO) connections are becoming an appealing low cost and high rate alternative to copper and fiber as the backhaul solution for wireless communication systems. To ensure a reliable cellular backhaul, provisions for redundant, disjoint paths between the nodes must be made in the design phase. This paper aims at finding a cost-effective solution to upgrade the cellular backhaul with pre-deployed optical fibers using FSO links and mirror components. Since the quality of the FSO links depends on several factors, such as transmission distance, power, and weather conditions, we adopt an elaborate formulation to calculate link reliability. We present a novel integer linear programming model to approach optimal FSO backhaul design, guaranteeing $K$-disjoint paths connecting each node pair. Next, we derive a column generation method to a path-oriented mathematical formulation. Applying the method in a sequential manner enables high computational scalability. We use realistic scenarios to demonstrate our approaches efficiently provide optimal or near-optimal solutions, and thereby allow for accurately dealing with the trade-off between cost and reliability

Aeronautical engineering: A continuing bibliography, supplement 122

This bibliography lists 303 reports, articles, and other documents introduced into the NASA scientific and technical information system in April 1980